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rojo's avatar

Can anyone give me some advice about an electrical problem.

Asked by rojo (24179points) September 2nd, 2013

I have a new renter who called me up and said that his oven did not work. Neither the broiler or the baking elements heated up. I had not had any prior complaints but maybe folks don’t use ovens much.
When I took it apart I found the terminal block for the 220v had melted through on the black wire and was a molten mass on the red but still attached.
When replacing the block I noticed that, although it was a three wire (three prong) plug, it had been wired up like a 4 wire (four prong) system but with the additional copper ground from the neutral as well.
The difference seems to be that on the 3 wire the neutral is grounded from the terminal block directly to the range while on the 4 wire it attaches to the terminal block only and a ground wire goes to the range. What I have is a neutral that ties to the terminal block and then is grounded to the range but the ground wire from the plug is also attached to the range through the tab.
I am not sure how it is wired in the plug and probably need to check but would having both the neutral and the ground connected together have caused the burning and melting? Would it have worked for a while before burning out? What else could have caused it?
Should I wire it in as a 3 prong only and cut off the ground where it comes out of the flex conduit?
Any help would be greatly appreciated.

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7 Answers

bossob's avatar

To meet current code, the range should have a four prong plug, and the supply should be 4 wire. By today’s codes, neutrals and grounds should never touch. (The old code said that the range could be grounded through the neutral.)

I’m not sure if you have an older 3 wire range. If you do, here’s an easy to read description of how to wire it for a 4 wire supply.

As for the block melting, it could have had corrosion build up on the terminal that caused it to heat up.

jerv's avatar

Cutting off the ground is an accident waiting to happen.

While there is a difference between the Neutral wire and the ground wire, had the system been totally ungrounded, anybody touching the stove would be shocked… possibly fatally!

In my time as an electrician, I’ve been belted a few times, and trust me when I say that 220 VAC is no joke. Please don’t electrocute anybody!

SpatzieLover's avatar

As a property manager, IMO, this is a job for an electrician. Is the rest of your electricity up to code?

jerv's avatar

@SpatzieLover I agree. The simple fact that this question was even asked tells me that the OP should just pony up a few bucks for a professional, especially given the potential lethality of their idea about the ground wire.

Of course, they might get lucky and not electrocute anybody, merely set the place on fire and burn it down… while the occupants sleep.

Yes, I’m a little touchy about electrical safety. I lost one home due to an electrical fire. Good thing the neighbors woke us up at 2:30 AM…

CWOTUS's avatar

The best advice is: Call an electrician OR replace the appliance. Depending on the age of the range / oven, this may be the best, cheapest and easiest advice, anyway, especially since you can buy a used and very serviceable stove for a couple hundred bucks, and it will last indefinitely.

I bought a used stove when I moved into my current home over twelve years ago, and it’s showing no signs of quitting.

bossob's avatar

The OP was smart enough to find and replace the damaged component, and smart enough to ask a question when he was in doubt. It sounds to me like he’s more than competent to make the repair himself. Residential wiring should be respected, but not feared. Interested DIYers learn about and perform safe electrical repairs every day.

@rojo, if you google “diy appliance repair” you’ll find all kinds of sites where electricians and appliance repairmen answer DIY questions. Your question is asked frequently.

It used to be that ground wires for range supplies weren’t required by the NEC, and ranges were grounded to the neutral. In 1996, it was decided there was a remote possibility that the grounded range could carry current (become electrified), so they began requiring 4 wire supplies to ranges for new construction and large remodel projects where the the old 3 wire could be fairly easily replaced with 4 wire. Existing, undisturbed 3 wire systems were grandfathered in.

rojo's avatar

Thanks for the advice all.

Follow-up:

In addition to replacing the melted terminal block which had been caused, I believe, by arcing because the black wire was loose at the block I replaced the entire plug with a new 3 wire plug on the premise that since the house was built in the 80’s and the outlet had a 3 wire cover plate, it was probably wired 3 wire and that someone had just rigged whatever they had when the range was installed. I then wired the new cord in at the back of the stove as detailed on the stove.
It did not fix the problem but it did fix the damage found and make me feel better. I am getting 240 to the range and up to the EOC but it is not making the connection to the elements. I believe the controller probably has some fried electronics as well. Part ordered and on its way.

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